This video will show you how to downgrade from the official firmware (version 5.03) to 5.00 m33 CFW (custom firmware). Pandora is not needed to perform these steps!
You need to mod your PSP in order to do this. This video does not show you how to mod your PSP beyond changing the firmware.
This only works on PSP-1000(fat) or a PSP-2000(slim).